Number of sets of exactly n positive integers <= 2n having a square element sum.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =8a(5) =24a(6) =74a(7) =238a(8) =786a(9) =2646a(10) =9071a(11) =31536a(12) =110967a(13) =394420a(14) =1414053a(15) =5107523a(16) =18568628a(17) =67894564a(18) =249513890a(19) =921134164a(20) =3414439996a(21) =12703212213a(22) =47419589969a(23) =177551521838a(24) =666655929561